I thought I'm misunderstanding it. It isn't caused by datamodel. I use the @Out error again. I'm confused. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4043452#4043452 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4043452